Mid 70's, plastic friction welding was a TOY - I watched that video a while ago, not sure if Fran mentioned it, but I think I did comment on her YouTube page about this - I had a toy called the Mattel SpinWelder - a little handheld thing with a 6V motor that ran off a lantern battery. Plastic trigger switch with simple contacts, and they supplied the 'welding rods' with little cups molded in to the drive end that you press-fit to the motor shaft. The various kits (I had one that build a Can-Am race car) has various beams and rods you welded together to form the framework, and there ere also, in the case of my car, body panels you welded to the frame. The rear wheels of the car had metal inserts for a flywheel effect, and there was a tri-star shaped tip that could attach to the motor and mated with the wheel hub to spin it up and then you could let it zip across the floor. Inevitably crashing into something and breaking piece off, requiring more welding. Since it ran on a 6V lantern battery, I built most of mine while camping.